Injection valve

ABSTRACT

An injection valve with a valve control module ( 2 ) adjacent to a nozzle module with a nozzle plate has a nozzle needle axially movable in a nozzle body. An intermediate element is pressed against the throttle plate by a spring disposed between the intermediate element and the nozzle needle and exerts an axial force on the nozzle needle in the closing direction. At least one outlet throttle is provided in the throttle plate, and at least one inlet throttle connected to a high-pressure region is provided, both of which throttles feed into a valve control chamber. The throttle plate has an enclosed raised area that delimits an inner chamber, constitutes a delimitation for the valve control chamber, and contains the inlet throttle.

PRIOR ART

The invention relates to an injection valve with a valve control moduleand a nozzle module, of the type generically defined by the preamble toclaim 1.

Injection valves of this kind are sufficiently known from the prior artand are particularly used in connection with common rail injectionsystems for diesel internal combustion engines.

An injection valve of the above-mentioned type known from the prior arthas a nozzle body of a nozzle module, which contains a nozzle needlethat can move in the axial direction in order to open and close theinjection valve. At its end oriented toward the combustion chamber ofthe internal combustion engine, the nozzle body is provided with anumber of injection openings that can be controlled by means of theaxially mobile nozzle needle. In addition, the injection valve isembodied with a valve control module that has a module housing andpiezoelectric actuator module provided therein, which are operationallyconnected to the nozzle module via a valve control chamber in anintrinsically known manner.

The piezoelectric actuator module is adjoined by a valve elementmechanism that transmits an adjustment path of the piezoelectricactuator module to a valve closing element. The valve element mechanismhas a first piston, a so-called adjusting piston, and a second piston, aso-called actuating piston, between which is provided a hydraulictransmission device or hydraulic coupler. The hydraulic coupler alsoserves to compensate for differences in axial length caused bytemperature differences.

The valve control module controls the nozzle needle by means of pressurechanges in the so-called valve control chamber; the pressure changes inthe valve control chamber trigger an axial movement of the nozzleneedle, which in turn opens or closes the injection openings of thenozzle body leading to the combustion chamber of the engine.

The pressure in the valve control chamber is set by means of twothrottles feeding into the valve control chamber, an outlet throttledisposed in a throttle plate and an inlet throttle disposed in a sleevethat delimits the valve control chamber and encompasses the nozzleneedle.

However, a disadvantage to this is that the tolerance ranges requiredfor a proper operation of the injection valve, in particular those inthe balancing of a diameter ratio between the inlet throttle and theoutlet throttle as a function of an opening pressure of the injectionpressure in the valve control chamber, can only be achieved by means ofa very costly testing and a high degree of complexity in terms ofproduction engineering, which incur high technical and apparatus-relatedexpenditures.

The object of the current invention, therefore, is to provide aninjection valve that is easy and inexpensive to produce.

According to the invention, this object is attained with an injectionvalve according to the features of claim 1.

ADVANTAGES OF THE INVENTION

The injection valve according to the invention, with the featuresaccording to the preamble of claim 1, in which the side of the throttleplate oriented toward the nozzle module has an enclosed raised area,which not only delimits an inner chamber, but also represents a boundaryfor the valve control chamber and contains the inlet throttle, has theadvantage that the outlet throttle and the inlet throttle are integratedinto a single component, i.e. the throttle plate, which makes itconsiderably easier to balance the diameter ratio of a diameter of theoutlet throttle and a diameter of the inlet throttle as a function of aninjection valve opening pressure in the valve control chamber.

In particular, it is possible to keep in store a selection of differentthrottle plates that are classed according to the diameter ratio oraccording to the ratio between the throttling action of the outletthrottle and the throttling action of the inlet throttle and, as afunction of an empirically determined opening pressure of a nozzlemodule, to select from among the classed throttle plates a throttleplate that “fits” and to pair it with this nozzle module.

Consequently, during the assembly of an injection valve, a balancing iscarried out between the opening pressure of the nozzle module and theratio between the throttling actions of the two throttles of the valvecontrol chamber; this balancing, which is necessary for the desiredfunction of the injection valve, is carried out in a simple mannerthrough the measurement of the opening pressure by a measuring deviceand the definite pairing with a component, i.e. the throttle plate.

Throttle plates or throttles disks of this kind, which are produced atthe same time as the inlet throttle and the outlet throttle for thevalve control chamber, are advantageously produced in one continuoussegment of a production line.

In comparison to injection valves known from the prior art, an injectionvalve according to the invention also has the advantage that a balancingwith regard to the diameter ratio between the diameter of the inletthrottle and the diameter of the outlet throttle is carried out withonly a single component.

It is also advantageous that the placement of the inlet throttle in theregion of the raised area of the throttle plate does not result in anysignificant change in the position of the inlet throttle as compared toan injection valve known from the prior art, which means that in orderto obtain an injection valve according to the invention, a knownstructural embodiment of an injection valve need only be provided with athrottle plate embodied according to the invention and with anintermediate element that is adapted to the throttle plate according tothe invention.

Other advantages and advantageous modifications of the subject of theinvention ensue from the specification, the drawings, and the claims.

DRAWINGS

An exemplary embodiment of the injection valve according to theinvention is shown in schematically simplified fashion in the drawingsand will be explained in detail in the subsequent description.

FIG. 1 shows a schematic longitudinal section through part of aninjection valve, and

FIG. 2 shows an enlarged detail X of the injection valve according toFIG. 1.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

FIG. 1 shows an injection valve 1 with a valve control module 2 and anozzle module 3. The valve control module 2 is embodied with an actuatormodule 4 that is depicted only partially; the actuator module 4 is apiezoelectric actuator unit. The actuator module 4 is adjoined by avalve element mechanism 5, which has an adjusting piston 6 and anactuating piston 7; between these two pistons 6, 7, a hydraulic chamber8 is provided, which functions as a hydraulic coupler or hydraulictransmission and as a compensation element for temperature-inducedfluctuations in length of the injection valve 1.

In addition, the injection valve 1 is embodied with a high-pressureregion and a high-pressure connection 9, via which a conduit 11extending in components 10A, 10B of the valve control module 2 issupplied with fuel at high common rail pressure, which is then suppliedto the nozzle module 3; the common rail pressure can be up to 1.6 kbar.

The injection valve 1 in this case is provided in an intrinsically knownmanner with a pressure-control valve, not shown in detail, that is usedto set a system pressure of a low-pressure region 30 of the injectionvalve 1. The system pressure of the injection valve 1 is preferably lessthan 30 bar and, depending on the current intended use, thepressure-control valve sets the level of the system pressure to arequired value that has a positive effect on the operation of theinjection valve.

The nozzle module 3 is embodied with a nozzle needle 12 that is disposedso that it can move axially in a nozzle body 13. According to thedepiction in FIG. 1, the nozzle body 13 rests against a throttle plate14 of the valve control module 2 and is attached to the valve controlmodule 2 by means of a nozzle coupling nut 15.

At its end oriented away from the valve control module 2, the nozzleneedle 12 cooperates with a valve seat 16 of the nozzle body 13 so thatwhen the nozzle needle 12 lifts away from the valve seat 16, injectionopenings 17 of the nozzle body 13 are opened and fuel is injected into acombustion chamber of an internal combustion engine.

During the injection event, the nozzle needle 12 in the nozzle body 13moves from the valve seat 16 toward the valve control module 2 and valveplate 14 counter to a spring force of a spring 18 that acts on thenozzle needle 12 in the closing direction of the nozzle needle 12.

The end of the spring 18 oriented away from the valve control module 2is supported by means of a disk 19 against a shoulder 20 of the nozzleneedle 12. At its end oriented toward the valve control module 2, thespring 18 rests against an intermediate element or a so-called springplate 21, which in turn rests against the throttle plate 14. Thethickness of the disk 19 can be used to influence the behavior of thespring 18, thus allowing manufacturing tolerances to be compensated forduring assembly of the injection valve 1 by making a definite choicefrom among the classed disks 19 kept in store.

The nozzle needle 12, the spring plate 21, and the throttle plate 14delimit a valve control chamber 22, which in this instance, communicateswith a respective inlet throttle 23 and outlet throttle 24 that are bothdisposed in the throttle plate 14.

FIG. 2 shows an enlarged view of the region of the injection valve 1labeled X in FIG. 1. In the region X, the side of the throttle plate 14oriented toward the nozzle module 3 has an enclosed, circumferentialraised area 26 that delimits an inner chamber 25 and, together with thespring plate 21 and an end region 12A of the nozzle needle 12, delimitsthe valve control chamber 22. In this instance, the raised area isembodied as an annular collar 26 that extends toward the spring 18 andprotrudes beyond an end surface 27 of the throttle plate 14 orientedtoward the nozzle module 3.

In the sectional view shown in FIG. 2, the inlet throttle 23 is disposedin the annular collar 26 as a result of which the high-pressure region 9of the injection valve 1 that encompasses the spring plate 21 isconnected to the valve control chamber 22 by means of the inlet throttle23. In addition, the outlet throttle 24 extends away from the valvecontrol chamber 22, i.e. from the inner chamber 25 of the annular collar26, in the direction of the low-pressure region 30 of the injectionvalve 1.

A minimal distance from a center line 44 of the inlet throttle 23 in theannular collar 26 to the end surface 27 of the throttle plate 14 shouldnot be less than 2 mm in order to provide enough space for an electrodeguide during the erosion used to produce the inlet throttle 23 in theannular collar 26. The diameter of the inlet throttle 23 preferably liesin a range from 0.15 to 0.25 mm; in the current instance, the inletthrottle has a diameter of 0.2 mm.

An end surface 28 of the annular collar 26 oriented toward the springplate 21 has a conically embodied cross-section in relation to a surface29 of the spring plate 21 oriented toward the throttle plate 14 so thatwhen the spring plate 21 contacts the annular collar 26, there is alinear contact between these two components, which is particularlyadvantageous for producing a seal between the valve control chamber 21and the high-pressure region 8. The contact between the spring plate 21and the annular collar 26 is produced by the spring 18, whoseprestressed installation position causes it to press the spring plate 21against the annular collar 26.

The end region 12A of the nozzle needle 12, which is guided so that itcan move axially in a guide 41 of the spring plate 21, is embodied witha smaller diameter than a region of the nozzle needle 12 disposedoutside the spring plate and encompassed by the spring 18. This steppingof the nozzle needle 12 on the side of the spring plate 21 oriented awayfrom the throttle plate 14 forms a shoulder 32, which constitutes astroke path limitation for the nozzle needle 12 when this nozzle needle12 moves in the opening direction of the nozzle module 3 and injectionvalve 1.

At a transition between the annular collar 26 and the end surface 27 ofthe throttle plate 14, the end surface 27 of the throttle plate 14 isembodied with a recess 33, which is provided among other things so thatthe end surface 27 of the throttle plate 14 can be machined with agrinding tool even in the region close to the annular collar 26.

The operation of the exemplary embodiment of an injection valve shown inFIG. 1 will be described below in connection with its use in a fuelinjection valve for internal combustion engines of motor vehicles; thefuel injection valve or injection valve 1 in the current embodiment isdesigned as a common rail injector.

In order to set an injection start, an injection duration, and aninjection quantity by means of fuel ratios in the fuel injection valve1, the valve element mechanism 5 is triggered by means of the actuatormodule 4, which is disposed at the end of the valve element mechanism 5oriented toward the valve control chamber and away from the combustionchamber. The piezoelectric actuator of the actuator module 4, not shownin detail, is composed of a number of ceramic layers in an intrinsicallyknown fashion and has an actuator head 42 at its end oriented toward thevalve element mechanism 5 and, at its end oriented away from the valveelement mechanism 5, has an actuator base, not shown, which is supportedagainst a wall of a valve housing of the injection valve 1.

In the position of the valve element mechanism 5 shown in FIG. 1, acontrol chamber 34 of the injection valve 1 is shut off from thelow-pressure region 30. The control chamber 34 contains a valve element35 of a control valve 36, which, when the actuator module 4 is withoutcurrent, rests in a sealed fashion against a first control valve seat 37that is embodied in the component 10A of the valve control module 2. Theconnection between the control chamber 34 and the valve control chamber22 via the outlet throttle 24 is open because the valve element 35 ispressed against the first control valve seat 37 by a spring mechanismand by the pressure prevailing in the control chamber 34. In thisposition of the valve element 35, the piezoelectric actuator is withoutcurrent and the injection valve 1 is closed by the contact of the nozzleneedle 12 against the valve seat 16 of the nozzle body 13.

If the actuator module 4, i.e. its piezoelectric ceramic, is suppliedwith current, then the length of the piezoelectric ceramic increases dueto the piezoelectric effect. This lengthening is transmitted in anintrinsically known manner from the valve element mechanism to the valveelement 35 so that the valve element 35 is lifted away from the firstcontrol valve seat 37 and slid axially toward a second control valveseat 38 embodied on the side of the throttle plate 14 oriented towardthe control chamber 34.

In this position of the valve element 35, the high-pressure region 9 isconnected to the low-pressure region 30 via the valve control chamber 22and the control chamber 34, and the pressure of the valve controlchamber 22 is relieved in the direction of the low-pressure region 30via the outlet throttle 24. The ratios of pressure and surface area inthe nozzle module 3 cause the nozzle needle 12 to lift away from thevalve seat 16 of the nozzle body 13.

In order to close the injection valve 1, the valve element 35 is placedin a sealed fashion against the first control valve seat 37 or thesecond control valve seat 38, thus closing the connection between thevalve control chamber 22 and the low-pressure region 30. In order toplace the valve element 35 in a sealed fashion against the first controlvalve seat 37, the current supply to the actuator module 4 isinterrupted, which cancels the lengthening of the piezoelectric ceramicof the actuator module. This is accompanied by an axial movement of thevalve element mechanism 5 toward the actuator module 4 and, as a resultof both the pressure in the control chamber 34 and a spring force of aspring element 43 acting on the valve element 35 in the direction of thefirst control valve seat 37, the valve element 35 is in turn pressed ina sealed fashion against the first control valve seat 37.

In this position of the valve element 35, the connection between thelow-pressure region 30 and the valve control chamber 22 is interruptedor closed. As a result, the pressure in the valve control chamber 22rises via the inlet throttle 23, approaching the pressure in thehigh-pressure region 9; starting from a definite pressure value in thevalve control chamber 22, the nozzle needle 12 is pressed against thevalve seat 16 of the nozzle body 13 in a sealed fashion, thus closingthe injection valve 1 and its injection openings 17.

The second position of the valve element 35 described above, whichcauses the injection valve 1 to close, is achieved by setting a currentsupply of the actuator module 4 in such a way that the lengthening ofthe actuator module 4 causes a sealing contact of the valve element 35against the second control valve seat 38 and the valve element 35 closesthe outlet throttle 24. As a result, the connection is simultaneouslyclosed between the valve control chamber 22 and the low-pressure region30 so that the pressure in the valve control chamber 22 increases viathe inlet throttle 23, thus causing the injection valve 1 to close inthe above-described manner.

The closing of the injection valve 1 through contact of the valveelement 35 against the first control valve seat 37 is preferable if aninjection phase into a combustion chamber of an engine has finished andthe intent is for no further injections to occur during this injectionphase.

The closing of the injection valve 1 through contact of the valveelement 35 against the second control valve seat 37 is preferable duringan injection phase that is comprised of a number of injections in rapidsuccession. This is due to the fact that the valve element 35 does nothave to be moved in opposition to the high-pressure of the valve controlchamber 22 in order to open the injection valve 1, as it does whenlifting away from the first control valve seat 37; instead, the highpressure in the valve control chamber 22 and the spring force of thespring element 43 both encourage the opening the connection between thevalve control chamber 22 and the control chamber 34 when the currentsupply to the actuator module 4 is reduced.

The nozzle needle 12 is guided in a sealed, longitudinally mobilefashion in a guide 40 of the nozzle body 13 and in the guide 41 of thespring plate 21; the two guides 40 and 41 are matched to each other inorder to prevent the axial movement of the nozzle needle 12 due to apossibly incorrect position of the nozzle needle 12 that would lead toincreased frictional forces between the nozzle needle 12 and the nozzlebody 13 and spring plate 21. In particular, the guide 41 of the springplate 21 is embodied as relatively short in the axial direction of theinjection valve 1, which offers a production cost advantage over thesleeve-like components embodied with longer guide regions known from theprior art.

The throttle plate 14 with the inlet throttle 23 and outlet throttle 24is a prefabricated, classed disk, which is embodied with a definitediameter ratio between a diameter of the inlet throttle 23 and adiameter of the outlet throttle 24 that assures a proper operation ofthe injection valve 1 for a particular opening pressure of the injectionvalve 1. The so-called opening pressure here is the pressure value inthe valve control chamber 22 with an open control valve 36 at which thenozzle needle 12 lifts away from the valve seat 16 of the nozzle body13.

In the injection valve according to the invention, it is thereforepossible to use an opening pressure of the nozzle module 3 and/orinjection valve 1 measured in a special measuring apparatus in order toselect a throttle plate with the ratio that is required for a properoperation of the injection valve 1, i.e. the diameter ratio between adiameter of the inlet throttle and a diameter of the outlet throttleand/or the ratio between the throttling actions of the inlet throttle 23and outlet throttle 24. Because of manufacturing tolerances, thisdiameter ratio or ratio between the throttling actions of the twothrottles differs from nozzle module to nozzle module. This is why anassembly process includes storing a selection of classed throttle diskswith different diameter ratios and pairing them with a nozzle module asa function of the opening pressure.

Throttle plates of this kind can be produced easily and inexpensivelysince the inlet throttle and outlet throttle are integrated into onework piece or a single component. In addition, this significantlysimplifies the adjustment of an injection valve during assembly.

For example, the operation of an injection valve can be adjusted by thepairing of throttle plates whose inlet throttles have a flow that isselected as a function of the determined opening pressure and issuitable for a proper operation of the injection valve. The diameter ofthe outlet throttle is adapted to the diameter of the inlet throttle sothat the diameter ratio of the throttles is constant in all throttleplates to be paired.

In addition, it is naturally also possible to adjust the operation ofinjection valves by means of throttle plates with varying diameterratios. The diameter ratio of the classed throttle disks is variedeither by changing the diameter of the inlet throttle, by changing thediameter of the outlet throttle, or by changing the diameter of both theinlet and outlet throttle.

A minimal distance from a center line of the inlet throttle 23 in theannular collar 26 to the end surface 27 of the throttle plate 14 shouldnot be less than 2 mm in order to leave enough room for an electrodeguide during erosion. The diameter of the inlet throttle lies in a rangefrom 0.15 to 0.25 mm and, in the current instance, preferably has adiameter of 0.2 mm.

In another embodiment of the injection valve that differs from theabove-described embodiment, the raised area of the throttle platepositively engages in at least some areas with a device of the nozzlemodule to permit radial adjustment of the valve control module inrelation to the nozzle module. This results in the advantageouspossibility of eliminating the centering pins preferably used ininjection valves known from the prior art to center the valve controlmodule in relation to the nozzle module in the region between thethrottle plate and the nozzle body of the nozzle module, and replacingthem with the raised area, which advantageously reduces the number ofparts of an injection valve, which in turn simplifies assembly.

1-10. (canceled)
 11. In an injection valve (1) with a valve controlmodule (2) and an attached nozzle module (3), which has a nozzle needle(12) that is disposed so that it can move axially in a nozzle body (13),wherein the valve control module (2) adjoins the nozzle module (3) witha throttle plate (14) and, in the region of an end of the nozzle needle(12) oriented toward the throttle plate (14), an intermediate element(21) is provided, which is pressed against the throttle plate (14) bymeans of a spring (18) that is disposed between the intermediate element(21) and the nozzle needle (12) and exerts an axial force on the nozzleneedle (12) in the closing direction, wherein at least one outletthrottle (24) is provided in the throttle plate (14) and at least oneinlet throttle (23) connected to a high-pressure region (9) is provided,both of which throttles feed into a valve control chamber (22), theimprovement wherein, on its side oriented toward the nozzle module (3),the throttle plate (14) has an enclosed raised area (26) that delimitsan inner chamber (25), constitutes a delimitation for the valve controlchamber (22), and contains the inlet throttle (23).
 12. The injectionvalve according to claim 11, wherein the intermediate element (21) isembodied as a spring plate, which rests against the end surface (28) ofthe raised area (26) on the throttle plate (14) oriented toward thenozzle module (3).
 13. The injection valve according to claim 11,wherein the nozzle needle (12) of the nozzle module (3) is guided in aguide (41) of the intermediate element (21) and when the nozzle module(3) opens, moves axially in the guide (41) of the intermediate element(21) so that the end (12A) of the nozzle needle (12) oriented toward thethrottle plate (14) engages in an inner chamber (25) of the raised area(26).
 14. The injection valve according to claim 12, wherein the nozzleneedle (12) of the nozzle module (3) is guided in a guide (41) of theintermediate element (21) and when the nozzle module (3) opens, movesaxially in the guide (41) of the intermediate element (21) so that theend (12A) of the nozzle needle (12) oriented toward the throttle plate(14) engages in an inner chamber (25) of the raised area (26).
 15. Theinjection valve according to claim 11, wherein, in the region of theintermediate element (21), the nozzle needle (12) has a shoulder (32),which, upon execution of a definite stroke path of the nozzle needle(12) during an axial movement of the nozzle needle (12) to open thenozzle module (3), comes to rest against the side of the intermediateelement (21) oriented away from the throttle plate (14).
 16. Theinjection valve according to claim 12, wherein, in the region of theintermediate element (21), the nozzle needle (12) has a shoulder (32),which, upon execution of a definite stroke path of the nozzle needle(12) during an axial movement of the nozzle needle (12) to open thenozzle module (3), comes to rest against the side of the intermediateelement (21) oriented away from the throttle plate (14).
 17. Theinjection valve according to claim 13, wherein, in the region of theintermediate element (21), the nozzle needle (12) has a shoulder (32),which, upon execution of a definite stroke path of the nozzle needle(12) during an axial movement of the nozzle needle (12) to open thenozzle module (3), comes to rest against the side of the intermediateelement (21) oriented away from the throttle plate (14).
 18. Theinjection valve according to claim 11, wherein the end surface (28) ofthe raised area (26) oriented toward the intermediate element (21) isembodied with a conical cross section so that a linear contact isproduced between the raised area (26) and the intermediate element (21).19. The injection valve according to claim 12, wherein the end surface(28) of the raised area (26) oriented toward the intermediate element(21) is embodied with a conical cross section so that a linear contactis produced between the raised area (26) and the intermediate element(21).
 20. The injection valve according to claim 13, wherein the endsurface (28) of the raised area (26) oriented toward the intermediateelement (21) is embodied with a conical cross section so that a linearcontact is produced between the raised area (26) and the intermediateelement (21).
 21. The injection valve according to claim 15, wherein theend surface (28) of the raised area (26) oriented toward theintermediate element (21) is embodied with a conical cross section sothat a linear contact is produced between the raised area (26) and theintermediate element (21).
 22. The injection valve according to claim11, further comprising a disk (19) for adjusting a spring force of thespring (18) between an end of the spring (18) oriented away from thethrottle plate (14) and a shoulder (20) of the nozzle needle (12). 23.The injection valve according to claim 12, further comprising a disk(19) for adjusting a spring force of the spring (18) between an end ofthe spring (18) oriented away from the throttle plate (14) and ashoulder (20) of the nozzle needle (12).
 24. The injection valveaccording to claim 13, further comprising a disk (19) for adjusting aspring force of the spring (18) between an end of the spring (18)oriented away from the throttle plate (14) and a shoulder (20) of thenozzle needle (12).
 25. The injection valve according to claim 18,further comprising a disk (19) for adjusting a spring force of thespring (18) between an end of the spring (18) oriented away from thethrottle plate (14) and a shoulder (20) of the nozzle needle (12). 26.The injection valve according to claim 11, further comprising a recess(13) in the throttle plate (14) at a transition between the raised area(26) and an end surface (27) of the throttle plate (14) oriented towardthe intermediate element (21).
 27. The injection valve according toclaim 13, wherein the guide (41) of the intermediate element (21) forthe nozzle needle (12) is matched to a guide (40) of the nozzle body(13) of the nozzle module (3) for the nozzle needle (12).
 28. Theinjection valve according to claim 11, wherein a ratio is set between adiameter of the outlet throttle (24) and a diameter of the inletthrottle (23) as a function of a pressure in the valve control chamber(22) at which the nozzle module (3) opens.
 29. The injection valveaccording to claim 12, wherein a ratio is set between a diameter of theoutlet throttle (24) and a diameter of the inlet throttle (23) as afunction of a pressure in the valve control chamber (22) at which thenozzle module (3) opens.
 30. The injection valve according to claim 11,wherein the raised area of the throttle plate positively engages in atleast some areas with a device of the nozzle module to permit radialadjustment of the control module in relation to the nozzle module.